Lifestyle behaviours of children and adolescents during the first two waves of the COVID-19 pandemic in Switzerland and their relation to well-being: a population-based study

Background: Previous studies assessing the impact of the COVID-19 pandemic on children's and adolescent's lifestyle focused mainly on the first wave in early 2020. We aimed to describe changes in adherence to recommendations for physical activity (PA), screen time (ST), and sleep duration over the first two waves of the pandemic (March-May 2020 and October 2020-January 2021) in Switzerland, and to assess the associations of these lifestyle behaviours with life satisfaction and overall health, as indicators of well-being. Methods: We included 3168 participants aged 5 to 18 years from four Swiss cantons. Participants or their parents completed repeated questionnaires and reported on their (child's) PA, ST, sleep, life satisfaction, and overall health. We analysed lifestyle behaviours in terms of adherence to international recommendations. We used linear and logistic regression models to assess the associations of number of recommendations met and adherence patterns with well-being indicators. Findings: Compared to the pre-pandemic period, the percentage of participants meeting the recommendations for PA and ST decreased strikingly during March-May 2020, while there was a slight increase in those meeting recommendations for sleep. During October 2020-January 2021, the percentage of compliant children for PA and ST increased but remained lower than before the pandemic. Participants meeting all three recommendations were more likely to report excellent health (OR: 1.87 [1.15-3.08]) and a higher life satisfaction score ({beta}: 0.59 [0.30-0.88]) than participants not meeting any recommendation. Adherence to recommendations for PA and sleep, PA and ST, and sleep and ST was similarly associated with both well-being indicators. Interpretation: We show a substantial impact of the COVID-19 pandemic on children's and adolescents' lifestyle behaviours with a partial recovery over time, and an association between lifestyle and well-being. Public health policies to promote children's and adolescents' well-being should target PA, ST, and sleep simultaneously. Funding: Corona Immunitas.